The optimization have been performed using FDTD Solution simulation. Unit cell of perfect silver particles array on top of Si layer were investigated. The absorption was calculated from the transmission monitors located at the Si surface and at the depth of 0,5 um. The changing parameters were NPs size and sufrace coverage. The determined optimal structre should contain 140 nm particles covering 10 % of the surface. Additional cases of 15 nm SiO2 spacing layer and canche in the integration range in Am 1.5 spectrum were analyzed as well. Next step was experimental approach to this optimal structures.